Hey, can someone please tell me what tool is to be used to check if the dual valve from a car at the junk yard works? Someone on here recommened that I try to get one from a junkyard first, but I forgot what the tool he said to use to check if they work first. It was supposed to check voltage or something I guess.[/align]

 

Your hand.Put climate control on hi,feel for hot water flow on both out hoses.Put on lo,feel for hot water to stop on both out hoses of duovalve.The ones running toward the heater core in the firewall.